Applying polyurethane foam or other elastomeric coatings may be accomplished by mixing mutually reactive fluids to form a foam that can cure on a substrate when the one or more fluids combine. Various devices and apparatuses have been developed to accomplish this application of foam, including spray guns. Merely exemplary spray guns and components are disclosed in U.S. Pat. No. 2,890,836, entitled “Apparatus for Applying a Mixture of a Plurality of Liquids,” issued Jun. 16, 1959; U.S. Pat. No. 3,263,928, entitled “Apparatus for Ejecting a Mixture of Liquids,” issued Aug. 2, 1966; U.S. Pat. No. 3,627,275, entitled “Apparatus for Producing Plastic Foam,” issued Dec. 14, 1971; U.S. Pat. No. 3,765,605, entitled “Apparatus for Ejecting a Mixture of Liquids,” issued Oct. 16, 1973; U.S. Pat. No. 3,876,145, entitled “Apparatus for Ejecting a Mixture of Plurality of Liquids,” issued Apr. 8, 1975; U.S. Pat. No. 4,377,256, entitled “Apparatus for Dispensing a Mixture of Mutually Reactive Liquids,” issued Mar. 22, 1983; U.S. Pat. No. 4,523,696, entitled “Apparatus for Dispensing a Mixture of Mutually Reactive Liquids,” issued Jun. 18, 1985; and U.S. Pat. No. 7,527,172, entitled “Plural Component Mixing and Dispensing Apparatus,” issued May 5, 2009. The disclosure of each of the above-cited U.S. Patents is incorporated by reference herein.
In certain situations it may be preferable to a user of a spray gun to have an air purgeable mixing chamber to clear out any residual mixed fluids to prevent clogging. In such guns, compressed air may be used to actuate an air piston between a dispensing position and a purging position. Furthermore, a user may find it preferable to include a pattern control tip such that the expelled mixed solution may be applied in different patterns. Such pattern control tips may also be preferably removable in such a manner that a user can substitute different pattern control tips quickly.
While several systems and methods have been made and used for spray guns, it is believed that no one prior to the inventor has made or used the invention described in the appended claims.
The drawings are not intended to be limiting in any way, and it is contemplated that various embodiments of the technology may be carried out in a variety of other ways, including those not necessarily depicted in the drawings. The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present technology, and together with the description serve to explain the principles of the technology; it being understood, however, that this technology is not limited to the precise arrangements shown.